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Double blinded, placebo-controlled, randomised prospective intervention trial : to investigate the effectiveness of Bioslim in weight-loss and the influence of branding and advertising on the placebo response

Lee, Tzu-Ting (2012-03)

Thesis (MNutr)--Stellenbosch University, 2012.

Thesis

ENGLISH ABSTRACT: It is estimated that 1.3 billion people worldwide are either overweight or obese, making this a global epidemic. An effective weight-loss method involves the lifestyle changes of increased physical activity and lowered energy intake. These changes are difficult to carry out and to maintain. As a result, there is a soaring demand for weight-loss aids, including dietary supplements, which exploit consumers’ eagerness to find an effortless weight-loss solution. These supplements are easily accessible, require no prescription and are heavily marketed to suggest that weight loss is achievable without exercise and dieting. One such dietary supplement, Bioslim, is tested in this study.
The aim of this study was to investigate whether Bioslim results in greater weight loss than a placebo, and whether the marketing of the Bioslim brand has an influence on the placebo response.
Overweight adults residing in Cape Town (n = 87) were recruited by advertising in community newspapers and setting up stands at shopping centres. The subjects were randomised into one of four groups: Bioslim in Bioslim packaging (n = 26), Bioslim in unbranded packaging (n = 22), placebo in Bioslim packaging (n = 17) and placebo in unbranded packaging (n = 22). At baseline, the subjects were given one of the four products and anthropometric measurements (weight, height and skinfold thickness) were taken. After four weeks, these measurements were repeated. The subjects also had to complete a questionnaire regarding their experiences.
The body mass index (BMI) for the total population was 31.90 kg/m2 (SD = 3.91) at baseline and 31.89 kg/m2 (SD = 3.92) at follow-up. None of the measured anthropometric variables had changed significantly after four weeks. When the total study group sample was analysed, based on the allocated drug treatment groups (active or placebo), neither group showed significant weight loss from baseline to follow-up. Twenty-three subjects from the Bioslim group and 21 from the unbranded group reported exercising during the trial. The total group’s exercise time correlated significantly with fat-mass reduction (r = -0.31, p = 0.004). Furthermore, when data was analysed separately for the active and placebo groups, the active group showed a significant correlation (r = -0.45, p = 0.0012), while the placebo group showed an insignificant correlation (r = -0.05, p = 0.77). The same was not reflected in weight loss (r = -0.007, p = 0.95). It is concluded that Bioslim is an ineffective weight-loss supplement: subjects receiving active pills evidenced no significant beneficial changes in weight, waist circumference or body composition. More than half of the subjects attempted dieting and exercising, but these efforts were insufficient to impact on weight loss. The marketing and packaging of Bioslim did not enhance the placebo effect.
One subject from the active group withdrew from the study, complaining of severe headaches and heart palpitations. There was no difference in adverse events reported by the remaining active and placebo group subjects.
In conclusion, this study emphasises the need for better regulation of the efficacy and safety of dietary supplements.